The present invention generally relates to superconductivity and more particularly, to a superconductive apparatus in which material or an element exhibiting superconductivity and a cooling element are incorporated.
It is known that when a certain electrically conductive material is cooled to low temperatures, for example, a Pb-Nb alloy is cooled to cryogenic temperatures substantially identical with that of liquid helium, superconductivity appears when electric resistance becomes zero. Therefore, if superconductivity is applied to switching elements or highly sensitive sensors, etc., such a remarkably excellent advantage is gained because these elements can be operated without power dissipation. On the other hand, at this time, since cryogenic cooling is necessary, the elements should be accommodated in a cooling device, i.e. a so-called cryostat employing liquid helium and liquid nitrogen. Since this cooling device is large in size, complicated and expensive, these elements are not being put to practical use and thus, superconductivity is not widely applied to general devices at present.
Recently, materials such as ceramics are found to exhibit superconductivity. It is expected that if these materials are employed, a superconductive apparatus operable at much higher temperatures than that of liquid helium can be obtained. However, even if these materials are used, it is indispensably necessary to provide means for cooling the materials to a considerably low temperature in order to induce superconductivity with high reproducibility such that the superconductive apparatus is made more reliable, thereby making the superconductive apparatus large in size and resulting in high production cost of the superconductive apparatus.